THAAD is able to intercept incoming missiles at endo- and exo-atmospheric altitudes, with a maximum engagement altitude of roughly 150 kilometers above the earth’s surface. The missile itself can travel at speeds over Mach 8, placing it in the “hypersonic” category. THAAD manufacturer Lockheed Martin is interested in developing an extended range THAAD variant to counter hypersonic glide vehicles, including China’s own WU-14. Unlike the current THAAD interceptor, which uses a single-stage rocket, the longer-range version would have two stages. The first stage would launch the interceptor to a high altitude in or above the Earth’s atmosphere, while a “kick stage” would propel the rocket toward the enemy missile.
Some missiles that have trajectories that are too low for the SM3 (MIA considered to be 100-120 km), but can be handled by the THAAD (MIA considered to be 40-50km). Similarly, THAAD requirements are really meant to take over the speeds and altitudes where the PAC-3 MSE cannot successfully intercept. While there is some overlap, particularly when it comes to the ER majority of their (SM3 and THAAD) engagement envelopes are distinct. Since the air density at 100k m is 1/2,000,000 to 1/3,000,000 of sea level, decoys that were deployed there could fall with the real warhead to 50-60km of altitude.
With an additional stage and an ability to loiter, THAAD [extended range] has been reported to have nine to 12 times existing THAAD coverage, and its increased velocity could potentially both counter hypersonic threats and have homeland missile defense applications, supplementing [Ground-Based Midcourse Defense],” said Thomas Karako, an analyst with the Center for Strategic and International Studies.
Lockheed is pushing for funding for the development of an ER version of the THAAD to counter maturing threats posed by hypersonic glide vehicles adversaries may employ, namely the Chinese WU-14, to penetrate the gap between low and high-altitude missile defenses. The company performed static fire trials of a prototype modified THAAD second booster in 2006 and continued to self-fund the project until 2008.
The current 14.5 in (37 cm)-diameter single-stage booster design would be expanded to a 21 in (53 cm) first stage for greater range with a second "kick stage" to close the distance to the target and provide improved velocity at burnout and more lateral movement during an engagement. Although the kill vehicle would not need a redesign, the ground-based launcher would have to be modified with a decreased interceptor capacity from eight to five.
Currently, THAAD-ER is an industry concept and not a program of record, but Lockheed believes the Missile Defense Agency will show interest because of the threats under development by potential adversaries. If funding for the THAAD-ER began in 2018, a fielded product could be produced in 2022. Although the system could provide some capability against a rudimentary hypersonic threat, the Pentagon is researching other technologies like directed energy weapons and railguns to be optimal solutions.
The Missile Defense Agency awarded Lockheed a $2 million study contract to flesh out a design concept and shape requirements for a potential extended-range variant of THAAD, which would add a new two-stage booster system to the current THAAD interceptor, according to Doug Graham, Lockheed Martin vice president of advanced programs for strategic missile defense systems.
In 2007 the Senate Armed Service Committee approved an increase of $105 million for the Terminal High Altitude Area Defense, THAAD, system to increase the missile production rate, begin the upgrade of the evolved THAAD interceptor, and to conduct an additional test. The THAAD system had shown good success in its testing program so far, and it held significant potential to defend many regions against most ballistic missiles. The bill would add $25 million for co-production of the Arrow missile, and added $10 million to study the suitability of the THAAD missile to serve as a follow-on to Israel's Arrow system.
- Apogee: 100 km - 1995 April 21
- Apogee: 60 km - 2006 July 12
- Apogee: 40 km - 2007 June 26
- Apogee: 20 km - 2010 June 29
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